You can get these wheels to fit

Its all in the tyres. I am running 15's and they fit (just) with 45 series tyres, but in hindsight I should have opted for 16's as you can get a 35 series and get the total diameter of wheel and tyre around the 50cm mark. I rekon 51-53 cms is the max diameter you can go without having to modify anything.
Here are mine at 55.5cms rolling diameter.